Modern flight deck displays for vehicles (such as aircraft or spacecraft) display a considerable amount of information, such as vehicle position, speed, altitude, attitude, navigation, target, and terrain information. In the case of an aircraft, most modern displays additionally display a flight plan from different views, either a lateral view, a vertical view, or a perspective view, which can be displayed individually or simultaneously on the same display.
The lateral view, generally known as a lateral map display, is basically a top-view of the flight plan, and may include, for example, a top-view aircraft symbol, waypoint symbols, line segments that interconnect the waypoint symbols, and range rings. The lateral map may also include various map features including, for example, weather information, terrain information, political boundaries, and navigation aids. The terrain information may include situational awareness (SA) terrain, as well as terrain cautions and warnings which, among other things, may indicate terrain that may impact the aircraft. The perspective view provides a three-dimensional view of the vehicle flight plan and may include one or more of the above-mentioned features that are displayed on the lateral map, including the terrain information.
Altitude data may be displayed as a numerical value that indicates the present altitude in appropriate units, such as feet or meters. An altimeter tape is a graphical element that can be used to display altitude information on a flight deck display element in an easy-to-read manner. An altimeter tape is typically rendered as a small window having a scrolling numerical range dynamically displayed therein. As the altitude of the aircraft changes, the altitude scale of the tape dynamically adjusts such that the current altitude is displayed at a designated location, e.g., near the center of the window. Thus, if the aircraft is flying at a constant altitude of 6500 feet, the altitude scale will appear stationary, with the number 6500 centered in the window. If the aircraft begins to descend, the altitude scale will begin to scroll within the window, the number 6500 will migrate towards the top of the window, and lower elevation numbers will appear near the bottom of the window and begin migrating upwards.
An aircraft might be subject to certain altitude constraints, depending upon the flight plan, the geographic location of the aircraft, etc. For example, an aircraft may be restricted such that it must fly at or above a designated altitude when in one geographical region, at or below a designated altitude when in another geographical region, or between upper and lower altitude boundaries when in yet another geographical region. As another example, when landing, an aircraft will have a target altitude that is associated with the particular landing location.